solve each part step by step and with explanation, then surely got thumbs up a) A full bridge thyristor rectifier circui

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solve each part step by step and with explanation,then surely got thumbs up
a) A full bridge thyristor rectifier circuit with fourthyristors is fed from single-phase 240 V ac supply. The circuitprovides variable voltage supply to an electrical heater windingwhich dissipates 3 kW. Sketch the waveforms of the current throughand voltage across the load, assuming a firing angle of about 30degrees for each half cycle.
b) Sketch the waveforms of the voltage across and the currentthrough the load if a diode is appropriately placed across the loadto permit free-wheel operation. Explain the waveforms.
c) Explain why three-phase rectification is better than singlephase. How does this affect the size of the filter capacitor?
d) Explain why the current drawn from the mains for a rectifiercircuit has significant harmonics.